Science Explains: Laurel or Yanny

The internet has been split again this week, but for something markedly less controversial than usual. You’ve have thought that the pronunciation of a word would have been fairly clear-cut, but the disagreement over Yanny/Laurel suggests that this is not the case. How can one word sound like two?

Back in 2015, we saw a precursor to this phenomenon in the form of #dressgate. In case you’ve forgotten, an image of a dress made its way around social media – some people saw it as blue and black, and some as white and gold. The difference in perception was based on the assumptions that the brain made about the illumination of the dress under different lighting conditions (there is no clue in the original picture as to how to interpret the colour of the light source). Here’s an article from the time if you fancy a more detailed explanation.

Now, this situation is essentially on the same lines, but it’s your ears that are playing tricks on you this team. The sound is an example of a ‘perceptually ambiguous stimulus’ – something that can be understood in two ways, and the mind can flip back and forth between the two interpretations, because there is a level of ambiguity as which is the ‘correct’ understanding. A famous example of this is Rubin’s Vase, an illusion in which it is possible to see both the online of a vase and two people facing each other.

The sound is an example of a ‘perceptually ambiguous stimulus’ – something that can be understood in two ways

Although the two words appear different, mapping out their sound waves shows that they both have a similar timing and energy content. A lot of sounds, including L and Y, are made up of several frequencies at once. When a person speaks, the shape of their vocal tract and the resulting frequencies are down to the placement of the tongue. Now, there is something called a formant frequency – the frequency that carries the most energy when a sound is made – and human normally produces three formants in everyday speech. The word, however, contains more, suggesting it has been carefully crafted to fool the ear (and leading to many explanatory videos which suggest that turning down the bass or affecting the frequencies can force one of the words out).

The sound contains aspects of both words, so why do we hear different things? This is, in part, down to the age of your ears. As we age, our ears are less able to hear higher frequencies – the sounds in Yanny play out a higher frequency than the sounds in Laurel, which would imply that younger people will be more likely to hear Yanny. There’s also the question of accents – in the video, the word is spoken in a North American computer-generated accent, but there are likely to be differences in how the words would naturally be spoken in Australian and British English.

There is something called a formant frequency – the frequency that carries the most energy when a sound is made – and human normally produces three formants in everyday speech

There’s also the question of external factors, according to Professor Hugh McDermott of Melbourne’s Bionics Institute: “When the brain is uncertain of something, it uses surrounding cues to help you make the right decision. If you heard a conversation happening around you regarding ‘Laurel’ you wouldn’t have heard ‘Yanny’.

“Personal history can also give an unconscious preference for one or another. You could know many people named ‘Laurel’ and none called ‘Yanny’.”

Here’s the thing – unlike in the case of the dress, there is no definitive answer here, because of how the word has been designed. The interesting question now is what makes a person sway one way or the other, and scientists are already thinking about it. Bharath Chanrasekaran, an associate professor in the Department of Communication Sciences and Disorders at the University of Texas, has already begun recruiting volunteers in both camps for an experiment, monitoring their brain waves while they listen to the audio clip. What started as a fun internet question could end up providing some interesting new insights into how the brain works.

The interesting question now is what makes a person sway one way or the other, and scientists are already thinking about it

If only we knew whether to thank Laurel or Yanny for it…